Russian women using a hand powered winnowing machine in a threshing barn. Note the board across the doorway to prevent grain from spilling out of the barn, this is the origin of the term threshold.[1] Painting from 1894 by Klavdy Lebedev titled the floor or the threshing floor (Гумно).

Grange Barn, Coggeshall, Colchester, England, originally part of the Cistercian monastery of Coggeshall. Dendrochronologically dated from 1237–1269, it was restored in the 1980s by the Coggeshall Grange Barn Trust, Braintree District Council and Essex County Council.

A bridge barn in Switzerland. The bridge (rather than a ramp) in this case also shelters animals.

A barn is an agricultural building primarily located on farms and used for many purposes, notably for the housing of livestock and storage of crops. In addition, barns may be used for equipment storage, as a covered workplace, and for activities such as threshing. The word barn is also used to describe buildings used for uses such as a tobacco barn or dairy barn. Byre is an archaic word for one type of barn meant for keeping cattle.[2]

The word barn comes from the Old Englishbere, for barley (or grain in general), and aern, for a storage place—thus, a storehouse for barley.[3] “Another word for 'barn' in Old English was beretun, "barley enclosure" (from tun: 'enclosure,' 'house',[4] or beretun (barton), also meaning a threshing floor.[5] However, the common English name for a grain storage building now is granary.

Modern barns may include a stable, from Latin stabulum ‘stall, fold, aviary’ (literally "a standing place,"),[6]byre (‘cow shed’, from bower which is from Old English bur— "room, hut, dwelling, chamber," from Proto-Germanic *buraz (cf. Old Norse bur "chamber," Swedish bur "cage," Old High German bur "dwelling, chamber," German Bauer "birdcage")...”,[7] or stall, “...place in a stable for animals," from Old English steall "place where cattle are kept, place, position," and Proto-Germanic *stallaz (cf. Old Norse stallr "pedestal for idols, altar," Old Frisian stal, Old High German stall "stand, place, stable, stall," German Stall "stable," Stelle "place".[8]

In the U.S., older barns were built from timbers hewn from trees on the farm and built as a log crib barn or timber frame, although stone barns were sometimes built in areas where stone was a cheaper building material. In the mid to late 19th century in the U.S. barn framing methods began to shift away from traditional timber framing to "truss framed" or "plank framed" buildings. Truss or plank framed barns reduced the number of timbers instead using dimensional lumber for the rafters, joists, and sometimes the trusses.[9] The joints began to become bolted or nailed instead of being mortised and tenoned. The inventor and patentee of the Jennings Barn claimed his design used less lumber, less work, less time, and less cost to build and were durable and provided more room for hay storage.[10] Mechanization on the farm, better transportation infrastructure, and new technology like a hay fork mounted on a track contributed to a need for larger, more open barns, sawmills using steam power could produce smaller pieces of lumber affordably, and machine cut nails were much less expensive than hand-made (wrought) nails. Concrete block began to be used for barns in the early 20th century in the U.S.[11]

Modern barns are more typically steel buildings. From about 1900 to 1940, many large dairy barns were built in northern USA. These commonly have gambrel or hip roofs to maximize the size of the hay loft above the dairy roof, and have become associated in the popular image of a dairy farm. The barns that were common to the wheatbelt held large numbers of pulling horses such as Clydesdales or Percherons. These large wooden barns, especially when filled with hay, could make spectacular fires that were usually total losses for the farmers. With the advent of balers it became possible to store hay and straw outdoors in stacks surrounded by a plowed fireguard. Many barns in the northern United States are painted barn red with a white trim. One possible reason for this is that ferric oxide, which is used to create red paint, was the cheapest and most readily available chemical for farmers in New England and nearby areas. Another possible reason is that ferric oxide acts a preservative[12] and so painting a barn with it would help to protect the structure.

With the popularity of tractors following World War II many barns were taken down or replaced with modern Quonset huts made of plywood or galvanized steel. Beef ranches and dairies began building smaller loftless barns often of Quonset huts or of steel walls on a treated wood frame (old telephone or power poles). By the 1960s it was found that cattle receive sufficient shelter from trees or wind fences (usually wooden slabs 20% open).

Half-timbered with wattle-work walls for ventilation. Stryd Lydan Barn, originally at Llannerch Banna, Flintshire, North Wales. Re-erected at the St Fagans National History Museum, Cardiff, Wales in 1951.

Stone barns are common in parts of the United Kingdom, United States, France, and some Mediterranean countries. The projecting stones are a style in part of England.

Abidiah Taylor Barn Chester County, Pennsylvania. Part of the Taylor-Cope Historic District. Built in either in 1724 (date stone) or 1744 (wooden beam investigation) is one of the oldest extant barns in the United States. Field stone walls.

The combination of brick quoins with flint walls is common in (mostly older) buildings in this area of the Chilterns, Oxfordshire, England.

A rare wall material is Cob which is similar to adobe. Devon, England.

The hay track developed in the early 19th century, here showing how the hay hood (roof extension) covers the track. The gable wall of this barn is missing.

In older style barns, the upper area was used to store hay and sometimes grain. This is called the mow (rhymes with cow) or the hayloft. A large door at the top of the ends of the barn could be opened up so that hay could be put in the loft. The hay was hoisted into the barn by a system containing pulleys and a trolley that ran along a track attached to the top ridge of the barn. Trap doors in the floor allowed animal feed to be dropped into the mangers for the animals.

This barn in Thuringia, Germany has two outshots forming the recess to the middle barn doors.

A farm may have buildings of varying shapes and sizes used to shelter large and small animals and other uses. The enclosed pens used to shelter large animals are called stalls and may be located in the cellar or on the main level depending in the type of barn. Other common areas, or features, of an American barn include:

The physics term "barn", which is a subatomic unit of area, 10−28 m2, came from experiments with uranium nuclei during World War II, wherein they were described colloquially as "big as a barn", with the measurement officially adopted to maintain security around nuclear weapons research.

"He couldn't hit the broad side of a barn" is a popular expression for a person having poor aim when throwing an object or when shooting at something.

To "lock the barn door after the horse has bolted" implies that one has solved a problem too late to prevent it.

"Were you born/raised in a barn?" is an accusation used differently in various parts of the English-speaking world, but most commonly as a reprimand when someone exhibits poor manners by either using ill-mannered language (particularly if related to manure), or leaving doors open.

"Your barn door is open" is used as a euphemism to remind someone to zip the fly of their trousers.

To "barnstorm" is to travel quickly around a large area making frequent public appearances.

Barns have been classified by their function, structure, location, or other features. Sometimes the same building falls into multiple categories.

Apple barn or fruit barn – for the storage of fruit crops

Bank barn – A multilevel building built into a banking so the upper floor is accessible to a wagon, sometimes accessed by a bridge or ramp.

Bridge barn or covered bridge barn – general terms for barns accessed by a bridge rather than a ramp.

Boô – A sheep-barn and dwelling in the Netherlands, seasonal or sometimes year round.

Pennsylvania barn (U.S.) of which there are sub-categories such as standard and sweitzer types. Also known as forebay or porch barns.

Cantilever barn – a type of log crib barn with cantilevered upper floor(s) which developed in Appalachia (U.S.A.)

Combination barn — found throughout England, especially in areas of pastoral farming and the standard barn type in America. This general term means the barns were used for both crop storage and as a byre to house animals.[13]

Crib barn – Horizontal log structures with up to four cribs (assemblies of crossing timbers) found primarily in the southern U.S.A.

Drying barns for drying crops in Finland and Sweden are called riihi and ria, respectively.

New World Dutch Barn – An ancient barn type in the U.S. Also see Dutch barn (U.K.) in Other farm buildings section below.

New England barn - a common style of barn found in rural New England and in the U.S.

English barn (U.S.), also called a Yankee or Connecticut barn – An ancient and widespread barn type in the U.S.

Granary — to store grain after it is threshed, some barns contain a room called a granary, some barns like a rice barn blur the line between a barn and granary.

Housebarn, also called a byre-dwelling – A combined living space and barn, relatively common in old Europe but rare in North America. Also, longhouses were housebarns.

Pole barn — a simple structure that consists of poles embedded in the ground to support a roof, with or without exterior walls. The pole barn lacks a conventional foundation, thus greatly reducing construction costs. Traditionally used to house livestock, hay or equipment.

Potato barn or potato house– A semi-subterranean or two story building for storage of potatoes or sweet potatoes.

Tithe barn — a type of barn used in much of northern Europe in the Middle Ages for storing the tithes — a tenth of the farm's produce which had to be given to the church

Threshing barn — built with a threshing floor for the processing and storage of cereals, to keep them in dry conditions. Characterised by large double doors in the centre of one side, a smaller one on the other, and storage for cereal harvest or unprocessed on either side. In England the grain was beaten from the crop by flails and then separated from the husks by winnowing between these doors. The design of these typically remained unchanged between the 12th and 19th centuries. The large doors allow for a horse wagon to be driven through; the smaller ones allow for the sorting of sheep and other stock in the spring and summer.[14]

A granary or hórreo — a storage space for threshed grains, sometimes within a barn or as a separate building.

Linhay (linny, linney, linnies) — A shed, often with a lean-to roof but may be a circular linhay to store hay on the first floor with either cattle on the ground floor (cattle linhay), or farm machinery (cart linhay). Characterised by an open front with regularly spaced posts or pillars.

Milk room or milk house — to store milk.

Oast houses — an outbuilding used for drying hops as part of the brewing process.

Shelter sheds — open-fronted structures for stock

Shippon — a shed which houses oxen and cattle. Has fodder storage above, regularly spaced doors on the yard side, a pitching door or window on the first floor.

In Germany some hay barns were kept away from urban areas due to the risk of fire. These areas are called a Scheunenviertel from the German name for a barn, Scheune, which translates as "barn quarter".[15] This barn quarter is in Steinhude, Germany

Old farm buildings of the countryside contribute to the landscape, and help define the history of the location, i.e. how farming took place in the past, and how the area has been settled throughout the ages. They also can show the agricultural methods, building materials, and skills that were used. Most were built with materials reflecting the local geology of the area. Building methods include earth walling and thatching.

Buildings in stone and brick, roofed with tile or slate, increasingly replaced buildings in clay, timber and thatch from the later 18th century. Metal roofs started to be used from the 1850s. The arrival of canals and railways brought about transportation of building materials over greater distances.

Clues determining their age and historical use can be found from old maps, sale documents, estate plans, and from a visual inspection of the building itself,noting (for example) reused timbers, former floors, partitions, doors and windows.

The arrangement of the buildings within the farmstead can also yield valuable information on the historical farm usage and landscape value. Linear farmsteads were typical of small farms, where there was an advantage to having cattle and fodder within one building, due to the colder climate. Dispersed clusters of unplanned groups were more widespread. Loose courtyard plans built around a yard were associated with bigger farms, whereas carefully laid out courtyard plans designed to minimize waste and labour were built in the latter part of the 18th century.[16][17]

The barns are typically the oldest and biggest buildings to be found on the farm. Many barns were converted into cow houses and fodder processing and storage buildings after the 1880s. Many barns had owl holes to allow for access by barn owls, encouraged to aid vermin control.

The stable is typically the second-oldest building type on the farm. They were well built and placed near the house due to the value that the horses had as draught animals

Modern granaries were built from the 18th century. Complete granary interiors, with plastered walls and wooden partitioning to grain bins, are very rare.

Longhouses are an ancient building where people and animals used the same entrance. These can still be seen, for example, in North Germany, where the Low Saxon house occurs.

Few interiors of the 19th century cow houses have survived unaltered due to dairy-hygiene regulations in many countries.

Old farm buildings may show the following signs of deterioration: rotting in timber-framed constructions due to damp, cracks in the masonry from movement of the walls, e.g. ground movement, roofing problems (e.g. outward thrust of it, deterioration of purlins and gable ends), foundation problems, penetration of tree roots; lime mortar being washed away due to inadequate weather-protection. Walls made of cob, earth mortars or walls with rubble cores are all highly vulnerable to water penetration, and replacement or covering of breathable materials with cement or damp-proofing materials may trap moisture within the walls.[18][19]

Gin gang or round house — an extension to a threshing barn. It contained a horse driven engine, used to power a threshing machine. Sometimes called a wheel house. Water power and wind power were also used to drive the machine, and by the 1850s portable steam engine machines were used. Horse-engines, original threshing or winnowing machines are exceptionally rare.